What s This about a Network?

What's This about a Network?

A network requires at least two computers linked in a way that enables them to talk to each other. Most networks use electrical wires of some type to convey signals and data between computers. However, numerous types of networking media, including wireless technologies and fiber- optic cables, also support networked connections. In other words, you can get from here to there in many ways on modern networks!

A network's key ingredients always include some type of physical connection that allows computers to talk (and listen) to some kind of communications medium. Even if that network medium is wireless, something must physically connect computers to an antenna or to a similar device that allows those computers to broadcast and receive signals.

But there's more to networking than hardware. Although cables and connections are essential, they are purely decorative and can serve no useful purpose without software. In the following sections, you find out a bit more about the hardware and software that make networks work.

No hardware means no connections!

First and foremost, networking requires working connections to enable computers to communicate with each other. Networking hardware creates connections between computers and a network and defines the medium (or media) that allows information to flow from sender to receiver.

Networking hardware covers a broad range of devices, many of which you may find on your networks. In the first part of this book, we help you understand the roles and functions these devices play on a network.

From the most basic perspective, computers need the following hardware to talk to each other on a typical network:

• A network interface card (NIC) plugs into a computer and attaches to a network cable (or other medium, if something else is used). It turns computer bits into signals on the wire for outgoing stuff and turns incoming signals into bits for incoming stuff.

• Connectors make it possible to attach a network interface to the network medium. For wireless media, connectors attach antennas or other broadcast devices to interfaces. Connectors bring all the separate pieces of networking hardware together, so to speak.

• Cables convey signals from sender to receiver, using either electrical signals for wire cables or light pulses for fiber-optic cable. In the case of wireless media, the medium consists of the broadcast frequencies used to transmit information between senders and receivers.

• Additional network devices tie bigger, more complex networks together. These devices range from relatively simple hubs used to interconnect interfaces on star-wired networks (see Chapters 4 and 7) to repeaters used to link individual cable segments, as well as bridges, routers, and gateways (see Chapter 7). Hardware plays an important role in networking. Not only does it attach computers to a network, but it also interconnects multiple networks to manage how and when data flows from one network to another.

A simple view of networking

Networking boils down to these three critical requirements:

• Connections include the necessary hardware to connect a computer to a network, plus cables (called the network medium ) that ferry messages between computers. The hardware that hooks a computer to a network is called a network interface . In most cases, attaching a PC to a network requires inserting an adapter board called a network interface card (NIC) . Without a physical connection, a computer can't use the network.

• Communications define rules that computers must follow to exchange and interpret information. Because each computer may run different software, interconnected computers need a shared language to enable them to exchange messages and data. Without shared communications, computers can't exchange data, even though they may share a common network medium.

• Services are what computers talk about. In other words, services represent what computers do for each other, including sending or receiving files, messages, print jobs, and so on. Unless computers can perform services for each other across a network, a computer can't respond to requests from other computers, nor can it request things from other computers.

 

Without software, networks don't work

Software lets computers access and use hardware, whether that hardware is used for networking- related functions or for other purposes.

By now, you should understand that hardware provides the necessary connections that make networking possible, and software supports the communications and services needed to access the hardware and the network to which the hardware is attached.

Many different types of software play a supporting role when networking modern computers. This software includes special-purpose programs called device drivers , which allow a computer to address a network interface and exchange data with that interface. The software collection also includes full-blown applications that can access data on a local computer or on a server across the network with equal aplomb. The software also includes a bunch of other stuff that sits between device drivers and applications.

Throughout this book, we show you how to recognize the various pieces of software involved in networking and how to best configure that software to work with Windows Server 2003 on a network.